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Version: 4.6.x

Create StorageClass(s)

This document provides step-by-step instructions for creating a custom StorageClass for OpenEBS Local PV Hostpath. It explains how to create the StorageClass using a YAML definition and highlights the use of the default openebs-hostpath StorageClass.

important

You can skip this section if you would like to use the default OpenEBS Local PV Hostpath StorageClass created by OpenEBS.

The default Storage Class is called openebs-hostpath and its BasePath is configured as /var/openebs/local.

  1. To create your own StorageClass with custom BasePath, save the following StorageClass definition as local-hostpath-sc.yaml

    apiVersion: storage.k8s.io/v1
    kind: StorageClass
    metadata:
      name: local-hostpath
      annotations:
        openebs.io/cas-type: local
        cas.openebs.io/config: |
          - name: StorageType
            value: hostpath
          - name: BasePath
            value: /var/local-hostpath
    provisioner: openebs.io/local
    reclaimPolicy: Delete
    volumeBindingMode: WaitForFirstConsumer

    (Optional) Custom Node Labeling​

    In Kubernetes, Local PV Hostpath identifies nodes using labels such as kubernetes.io/hostname=<node-name>. However, these default labels might not ensure each node is distinct across the entire cluster. To solve this, you can make custom labels. As an admin, you can define and set these labels when configuring a StorageClass. Here's a sample storage class:

    apiVersion: storage.k8s.io/v1
    kind: StorageClass
    metadata:
      name: local-hostpath
      annotations:
        openebs.io/cas-type: local
        cas.openebs.io/config: |
          - name: StorageType
            value: "hostpath"
          - name: NodeAffinityLabels
            list:
              - "openebs.io/custom-node-unique-id"
    provisioner: openebs.io/local
    volumeBindingMode: WaitForFirstConsumer

    note

    Using NodeAffinityLabels does not influence the scheduling of the application Pod. Use Kubernetes Allowed Topologies to configure scheduling options.

    (Optional) File Permissions​

    By default, Local PV Hostpath creates the volume directory with 0777 permissions. For some workloads these permissions are wider than necessary. Use the FilePermissions config to set the permissions that the volume directory is created with:

    apiVersion: storage.k8s.io/v1
    kind: StorageClass
    metadata:
      name: local-hostpath
      annotations:
        openebs.io/cas-type: local
        cas.openebs.io/config: |
          - name: StorageType
            value: "hostpath"
          - name: BasePath
            value: "/var/local-hostpath"
          - name: FilePermissions
            data:
              mode: "0770"
    provisioner: openebs.io/local
    reclaimPolicy: Delete
    volumeBindingMode: WaitForFirstConsumer

    With the above StorageClass, the directory of every volume provisioned by it is created with 0770 permissions.

    note

    The permissions are applied when the volume directory is created, so changing FilePermissions later does not affect volumes that already exist.

    FilePermissions cannot be set through the Helm chart values for the default openebs-hostpath StorageClass. To use it, create a custom StorageClass as shown above, or set it for an individual volume through a PVC annotation.

  2. Edit local-hostpath-sc.yaml and update with your desired values for metadata.name and cas.openebs.io/config.BasePath.

    note

    If the BasePath does not exist on the node, OpenEBS Dynamic Local PV Provisioner will attempt to create the directory, when the first Local Volume is scheduled on to that node. You must ensure that the value provided for BasePath is a valid absolute path.

  3. Create OpenEBS Local PV Hostpath Storage Class.

    kubectl apply -f local-hostpath-sc.yaml

  4. Verify that the StorageClass is successfully created.

    kubectl get sc local-hostpath -o yaml

Restrict Volume Placement Using Allowed Topologies​

By default, a Local PV Hostpath volume can be provisioned on any node in the cluster. If the BasePath is present on certain nodes only, then make use of topology to tell the list of nodes where the path is available. As shown in the below storage class, we can use allowedTopologies to provision volumes on the specified nodes only.

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: local-hostpath
  annotations:
    openebs.io/cas-type: local
    cas.openebs.io/config: |
      - name: StorageType
        value: "hostpath"
      - name: BasePath
        value: "/var/local-hostpath"
provisioner: openebs.io/local
volumeBindingMode: WaitForFirstConsumer
allowedTopologies:
- matchLabelExpressions:
  - key: kubernetes.io/hostname
    values:
      - worker-2
      - worker-3

The above storage class tells that the BasePath is available on nodes worker-2 and worker-3 only. Volumes of this StorageClass will be provisioned and scheduled on those nodes only.

Unlike NodeAffinityLabels, allowedTopologies also influences the scheduling of the application Pod.

To set allowedTopologies on the openebs-hostpath StorageClass created by the Helm chart, use the localpv-provisioner.hostpathClass.allowedTopologies value:

localpv-provisioner:
  hostpathClass:
    allowedTopologies:
      - matchLabelExpressions:
          - key: kubernetes.io/hostname
            values:
              - worker-2
              - worker-3

Apply the updated values:

helm upgrade openebs openebs/openebs --namespace openebs -f values.yaml

Support​

If you encounter issues or have a question, file a Github issue, or talk to us on the #openebs channel on the Kubernetes Slack server.

See Also​